The present invention relates to an optical disk reproducing device, and in particular an optical disk reproducing device which is capable of changing the linear velocity in accordance with the vibration of the device.
The linear velocity at which commercially available optical disk reproducing devices can operate is increasing year by year. In the case of CD-ROM drives for use with personal computers, the velocity is increasing from ×1, to ×2, ×4, ×6, and so on, and many of the CD-ROM drives are designed to operate at a selected one of a plurality of linear velocities.
The rotational velocity of the disk increases with the linear velocity. While the rotational velocity at the inner radial part is about 500 rpm with the standard velocity (×1 velocity), it is as high as 3000 rpm with the ×6 velocity. With the increase in the velocity, vibrations increase and may become problematical. The increased vibrations may affect or disable the signal reading. The vibrations are caused by various factors such as eccentricity of the disk, variation in the position at which the disk is held, and unevenness in thickness of the disk. For instance, a commercially available CD-ROM disk with a nominal thickness of 1.2 mm has a thickness difference of 0.1 mm between the maximum and minimum thicknesses.